How to grow Gladioli

Originating from hot, dry climates in South Africa and Mediterranean countries. Gladioli like to have good drainage and plenty of sunshine in order to excel in the garden. If you live in a milder part of the UK, it is possible that bulbs will happily remain in a well-drained spot over winter, although it is advisable to lift them over winter and replant them in spring if in doubt.

These bright and eye-catching blooms are often referred to as Sword Lilies – due to the shape of the foliage (not dissimilar to bearded iris with elongated, pointed leaves). Sadly, these delightful blooms spent a while being ‘unfashionable’ amongst gardeners, whilst remaining a favourite with florists. They are now, fortunately, returning to favour with more exotic and unusual varieties such as Gladiolus byzantinus, along with rich and exciting colours of more traditional ‘glad’, being readily available.

The flower spikes are tall and hold a real presence in the border – especially with their large, trumpet shaped multiple blooms which are often enhanced by intriguing ombre effects. Perfect for bringing colour to a sunny herbaceous border and providing good contrast with grasses and other flowering plants. Gladioli also look good in containers and make excellent cut flowers if you are fortunate enough to have a cutting garden.

It is recommended that gloves are warn when handling the bulbs as they can be an irritant to the skin.

Key Information

Position

Soil Conditions

Flowering Period

Hardiness

Where & when to plant Gladioli

For best results, plant in autumn or spring. An autumn planting is suitable for those gardening in ‘mild’ conditions. (Broadly speaking, this is the southern half of the UK). For those liable to very cold winters or waterlogged ground, it is best to wait until spring. (This is generally the northern half of the UK, or anyone gardening on heavy, clay soil). It is also wise to check the cold tolerance level of your chosen gladioli first as some and fully hardy (such as gladiolus byzantinus) whilst others are considered susceptible when temperatures drop below -5°C. If growing in a container, then planting can be done all year-round providing watering is closely monitored.

Gladioli are happiest in a free draining soil which is able to retain some moisture and fertility. These bulbous perennials will not thrive in heavy or water-logged environments and are likely to rot away if left in wet conditions over winter.

How to plant Gladioli

Clear the area of weeds
Before planting add well-rotted organic matter to the soil and dig in – this will increase moisture retention during drier months
Alternatively, if you have poorly draining soil, add some mulch to help with better drainage
Using a trowel or dibber plant bulb 10-15cm deep and 10cm apart with the pointed end facing upwards
Backfill the hole with soil, tamping down gently
If planting en masse then scatter/broadcast bulbs prior to planting for a more natural look
Water in to settle soil and continue to water when in full growth

What to plant with Gladioli

Gladioli are at home in the informal jostle of a cottage-garden-style planting scheme where they can mingle with hollyhocks, delphiniums and lupins for a sea of spires. Alternatively mix it with grasses, heuchera and smaller shrubs for a modern border.

If you would like any further planting ideas or growing advice for your aconitum, please contact our friendly and knowledgeable Customer Care Team - who will be more than happy to help you.

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How to care for Gladioli

Pruning and Deadheading

Once gladioli have finished flowering, they should be cut back to about 8-10cm in height then lifted out of the ground or pot into trays or onto newspaper. They can then be cured or dried, which will preserve them ready for re-planting the following spring. Store bulbs in onion nets so that air can circulate through and keep them in a cool dry place until next required. When you come to replant you may find that there is an old, spent bulb attached to the new, fresh one – simply discard the old and replant the new.

Watering

Watering is only required when gladioli are in their growth phase during the summer.

Cold Protection

Most gladioli are half-hardy and it is, therefore, wise to lift them in colder parts of the UK. In milder areas a thick winter mulch will suffice. Gladiolus byzantinus is fully hardy and so does not require lifting.

Pests and Diseases

Gladioli is relatively free of pests and diseases although, like most plants, it is vulnerable to certain fungi, virus and insect damage.

Storage rot - corms may become soft during storage or be covered with bluish-green fungal growth. Control involves careful selection of clean, well-ripened corms for storage. It is wise to inspect the corms again carefully after storage and destroy any corms that appear unhealthy
Caterpillars - can also be a pest and often attack flower buds, chewing a hole through the entire bud and the petals held inside. Diligent inspection and removal is the best prevention
Scab and rot – other fungus can attack the corms when they are in the ground. Whilst proprietary treatments are available the most effective treatment is to carefully discard infected plants and corms so as not to allow these issues to spread further. Keep a watchful eye on any replanted gladioli in the same area is some fungus can remain in the soil and return to new stocks. If this is the case – remove and replant fresh corms elsewhere in the garden

How to propagate Gladioli

There are two gladiolus propagation methods: germinating seeds and growing new plants from divided corms. The method you choose depends on how many flowers you want to grow and how much time you’re willing to invest.

We recommend propagating by corm division as the easiest route:

Each corm will have a number of baby corms, known as cormels or cormlets, attached to the bottom. When you remove these cormlets and plant them separately, they’ll grow to flowering size in a couple of years. This is simple, straightforward and gives relatively quick results.

Alternatively, you can plant seeds about six weeks before the last frost in the spring. Place a single seed in a P9 pot fill with potting compost and cover with a sprinkling of soil. Water well and cover with plastic to create a ‘mini-greenhouse’. Once the seed has germinated and has leaves remove the plastic and place pot in a sunny spot. Grow outdoors for the first year then dig up the corm and store as usual. Plant this small corm outdoors for another 2 successive years (lifting and storing as with others). By the 2^nd or 3^rd year your corm should be large enough to produce a flower spike.

Common Aconitum Questions:

Do I need to stake my gladioli?

Taller species may need staking, though most will not require this unless grown in a windy spot.

Is it safe to plant gladioli in a family garden?

Gladiolus ‘Thalia’ can be harmful to smaller children and is toxic to cats and dogs. Contact with skin may cause irritation so wear gloves when handling.